Arc lamp and the like



Oct. 2, 1951 A. BERGMANN ARC LAMP AND THE LIKE Filed May 1, 1948 IN VEN TOR.

ANDREW BERGMANN ATTORNEY Patented Oct. 2, 1951 UNITED STATES PATENT OFFICE ARC LAMP AND THE LIKE 'Andrew Bergmann, Cheektowaga, N. Y. Application May 1, 1948, serial No. 24,499 6 Claims. (01. 14 68) This invention relates to are lamps and similarapparatus employing one or more movable electrodes and control means therefor. More particularly the invention relates to manually operable control means and to automatically operable control means for adjusting the electrode or electrodes of such apparatus for effecting an arc of proper predetermined size at a predetermined location and for advancing said electrode or electrodes for maintaining the are substantially constant as the electrode or electrodes wear away during use of the apparatus. The invention is especially useful in apparatus where substantially uniform illumination is of utmost importance.

Arc lamps, for example, have been employed for illumination purposes for many years, particularly in places Where high intensity sources of illumination were desirable, and various manual and automatically operable mechanisms have been provided for controlling the movement of the electrodes and for compensating for the Wearing away thereof during operation of the device. Also the electrode or electrodes of welding equipment have been similarly controlled. Some of such devices of earlier construction have had controls which have operated fairly satisfactory for maintaining the gap within close limits during burning of the are but these controls were expensive, complicated and of considerable size and bulk. On theother hand, other devices of earlier construction have not been satisfactory because of I their lack of sensitivity or, in other words, because of their inability to automatically provide the substantially constant size are de-- sired.

It is, accordingly, an object of the present invention to provide manual and automatically operable control means for moving one or more electrodes of an arc lamp, welding equipment or the like, separately or simultaneously as the case may be, into a proper operative position and for automatically advancing same for maintaining a substantially constant predetermined gap spacing at the arcing tips or terminals of the device.

It is a further objectof the invention to provide for such apparatus mechanical driving means for moving the electrode or electrodes of the arc lamp,or similar apparatus, and sensitive electrical control means therefor which will automatically advance one or more of said electrodes in a step by step manner to effect an are, if need be, and to maintain within predetermined limits the size of the arc during extended operation of th app t s It an' additional object of the invention to provide in an arc lamp or the like compact, em client and inexpensive mechanical and electrical means for enabling manual advancing and adjusting of the electrode orelectrodes thereof and for automatically maintaining. the arc size within small predetermined limits during operation of the apparatus, said electrical and mechanical means being positive in action and of such sensitive character as toeffect an incrementv offorward mov'ement of the electrode or electrodes when [an increase in the size of the gap. of as little as fone half millimeter occurs during burning of the arc.

, Other'objects and advantages of the .invention will appear from the detailed description which follows when taken in conjunction with the accompanying drawing in which:

l ig. l is a side elevational and partly schematic view of an arc lamp embodying the present invention; and

Fig. 2 is a vertical sectional view taken substantially on line 2'2 of Fig. 1.

Referring to Fig. 1 in detail, the numeral It! indicates generally a; supporting base which may be formed of either conductive or non-conductive material as desired. In the present case, it is shown formed of heavy sheet metal provided with peripheral stiffening flanges so that an electrode supporting bracket or block l2. may be secured to an upper flange [3 thereof and a similar bracket or block [4 may be secured to a forward sloping flange It in such a manner as to position electrodes [3 and 2b in suitable predetermined angular relation relative to each other. The electrodes are arranged so that an arc may be formed between ends or terminals 18' ,and 20' thereof for forming a concentrated light source at a predetermined point 2il which may be, for example, the focal point of acondenser lens system, the first lens element of which is indicated by the numeral 22. Brackets J2 and I4 are secured to the supporting base ID by bolts or other suitable means and when this supporting member It] is of conductive material the brackets and securing means may be electrically insulated therefrom by insulating materials such as indicated at numerals 23' and 24. A ceramic heat shield 25 may be employed as shown, if desired.

Each electrode supporting bracket l2 and I4 is provided with an electrode advancing mechanism and since these are of similar construcubn eniy one will be described in detail. A shaft 26 is arranged to extend transversely through and is journalled in the bracket I2" and has keyed or otherwise secured on an intermediate portion thereof a grooved driving wheel 28 for moving the electrode |8 (which is generally formed of carbon), in either a forward or a reverse direction. Manual adjustment in either direction can be readily effected by a suitable hand wheel 30 of non-conductive material secured to the outer end of shaft 26. Pressure rollers 32 carried by a floating U-shaped saddle 4 and vertically slidable through a limited distance in a recess 36 in bracket l2 bear against electrode IS. The pressure rollers and saddle are urged toward driving wheel 28 by suitable means, such as coiled springs, one of which is shown at 38. Obviously a wheel without a groove could be used instead of grooved wheel 28, if desired. In either case suitable guiding means will be provided for maintaining the electrode in proper alignment with point 2|.

An actuating lever 40 for advancing the elec trode |8 toward the focal point 2| of the optical system is pivotally mounted upon a thrust collar 4| on a bushing 42 releasably secured upon shaft 28. Also secured upon the bushing 42 is a rotatable fine toothed gear or ratchet wheel 44 and between this ratchet wheel and the thrust collar 4| is a spring washer or the like 46. A pair of lock nuts threaded onto bushing 42 are adjusted to provide proper pressure between the thrust collar, spring washer and ratchet wheel so that this wheel will have suitable frictional engagement with a flange 48 integral with bushing 42. The washer presses wheel 44 against flange 48 with sumcient pressure to effect a driving engagement therebetween and bushing 42 is secured upon the shaft 26 in such a manner as to provide a small amount of frictional resistance, through the medium of a spring washer 49 or the like, between the bushing and bracket l2 for preventing undesired movement of the electrode associated therewith. A spring pressed pawl 50 is carried by lever 40 in such a way as to provide a positive one-way driving engagement with wheel 44 when said lever swings upwardly upon the thrust collar on bushing 42 and about shaft 26 as a center.

As stated previously, the mechanism for actuating the electrode 20 is generally similar to that just described for moving electrode I8. It will be noted, however, that actuating lever 52 therefor is shorter and is provided with a spring pressed pawl 54 which faces in the opposite direction for effecting one-way rotation of gear or ratchet wheel 56 on shaft 51 in the opposite direction for advancing electrode 20 toward focal point 2|. An actuating lever 58, pivoted at 59 upon the supporting base l and formed of non-conductive material, is arranged to actuate levers 40 and 52 in opposite directions through the medium of adjustable means 60 and 62, respectively, for advancing the electrodes. Adjustment means 60 acts through the medium of a thrust rod 63 for effecting movement of the lever 40 and spring means 64 connected to a non-conductive pin 64 on the base serves to urge the lever in its reverse direction. A like spring 85 is similarly provided for swinging lever 52 in its reverse direction. Instead of lever 58 and the anchoring pins for the springs 54 and 65 being formed of non-conductive material, the levers 40 and 52 could be of such material and would give an equivalent result.

The locating of the pivot 59 intermediate the adjustable means 60 and 62 and the length of the levers 40 and 52 may be proportioned to give different predetermined rates of advance to the electrodes l8 and 20 in accordance with their respective normal burning rates. In one preferred form of the invention employing a standard 5 mm. diameter, 8 inch horizontal carbon and a standard 8 mm. diameter, 4 /2 inch vertical soft core carbon and operating on a 45 volt A. C. current at approximately 9.7 amperes, the best rate of advance for the horizontal carbon was found to be approximately 2.2 times the rate of the vertical carbon. This enabled the arc to remain at point 2| during the entire burning of the carbon and while the carbons were automatically advanced by the control mechanism.

Electrical control means for operating the lever mechanism just described in a step by step manner to advance the electrodes l8 and 20 comprises a solenoid 66 slot-and-pin connected at 68 to the lower end of lever 58. This solenoid is of such construction as to provide a strong driving stroke in the electrode advancing direction and the supply of electrical current to this solenoid is controlled by a precision snap-action switch 10, of the type commonly referred to as a micro-switch, connected in series therewith. The solenoid 66 and switch ll] are connected directly across the main current supply line for the instrument which may be, for example, a conventional 110 A. C. source controlled by a main switch 12.

When such a source of energy is employed for the lamp, it will be desirable to use a relatively large load resistor in series with one of the main conductors 13, or 14, leading from the switch 12 to one of the electrode supporting brackets. Such a resistor is shown at 15 and, as indicated, is preferably housed in a casing separate from the arc lamp so that it may be spaced a few feet from the lamp and connected thereto by flexible leads 15.

This resistor 15 serves to reduce the 110 volt current down to a suitable working voltage between approximately 40 and volts. This voltage range is preferred since a sufficient electromotive force must be present to maintain an arc of proper size across the gap between tips l8 and 20 and on the other hand, should not be so high as to produce excessive sputtering and unnecessary radio interference. The resistor 15 will generate considerable heat and thus is preferably spaced from the lamp. The resistor 15 has been shown as adjustable but such adjustment would ordinarily be a factory adjustment depending upon the character of the source of electricity available at the locality at which the instrument is to be employed. Normally it would be adjusted once and thereafter remain undisturbed.

In order to provide an exceedingly sensitive control circuit for controlling switch 10 and the power solenoid 66, there is provided a second precision snap-action or micro-switch 11 which is adjustably connected at 18 to the movable armature 66 of the solenoid 66. This switch is normally in a circuit closing position and the connection 18 is adjusted so that the electrical circuit controlled thereby will be interrupted as the armature 66 completes its inward (upward) driving stroke. Connected in series with microswitch 11 are a sensitive horizontally disposed control solenoid 19, and an adjustable resistor 8|. These three parts in series are in turn connected to main conductors 13 and 14 leading to the electrode supporting brackets l2 and I4 respectively. This in effect places these three parts 5, in a. control circuit 85 in parallel with the arc circuit.

Since micro-switch 11 is normally in its circuit closing position, it will be readily apparent that at such times and while main switch 12 is closed a current will flow through this control circuit. The purpose of adjustable resistor 8| is to regulate the total resistance in the control circuit 85 and this in turn will determine the normal predetermined length of the are which is to be maintained within close limits across the gap. By adjusting resistor 8| to increase or decrease the amount of electrical resistance in the control circuit 85 the normal spacing of the gap may be increased or decreased as desired.

If the electrode tips are separated a greater amount than that called for by the particular setting of the resistor 8| the resistance across the gap will be so high that the volta e or potential in the control circuit will build up sufficiently to draw armature 19 of control solenoid l9 inwardly from its rest position enough to snap the normally opened micro-switch 10 to its closed position, allowing an energizing of power solenoid 66, which in turn will have its full power available for actuating the mechanical driving mechanism.

As the armature of the solenoid 66 moves inwardly to effect a single forward stroke of the 'driving mechanism the connection 18 at the opposite end of the armature will cause microswitch 11 to snap to a circuit opening position. This action interrupts the flow of current through control solenoid 19 which in turn allows the armature thereof to be moved outwardly by a pivoted arm 16' under the resilient pressure of the micro-switch plunger 83 tending to allow micro-switch 10 to return to its outer or open position. This in turn de-energizes power solenoid 66 allowing it to return to its initial position. Adjustment screw 82 on pivoted switch arm 10 serves to regulate the normal outer position of the armature 19' just allowing microswitch to return to open position and screw 84 limits to a minimum the amount of over travel of the armature after micro-switch 10 has snapped to its circuit closing position. Furthermore it will be noted that armature 19' is horizontally disposed and positioned partly out of the solenoid 10 so as to have a maximum of freedom of movement and the greatest possible sensitivity. Also it will be noted that the lever arm distance from the pivot to hinge connection between arm 10 and the armature 19 is many times greater than the lever arm distance to the plunger 83. In fact while the drawing, for clearness, does not show the exact lever arm lengths preferred, it is well to note that a ratio in the neighborhood of 28 to 1 gives good sensitivity. This will give great mechanical advantage for operating switch 10 and while the armature will travel only a slight amount inwardly it will, nevertheless, operate the switch 10 when the parts are properly adjusted. In place of the resistor shown at 8! a more readily operable type could be employed in apparatus where it is desired to change the gap spacing occasionally.

Since the control circuit is connected in parallel with the electrodes and gap 'therebetween, only a relatively small current need flow through control circuit 85 to operate the control solenoid 19. However when the voltage in this circuit increases sufficiently, directly influenced by the increase in resistance across the gap between elec- 6 trode terminals 18' and 20', the armature I! will bedrawn in enough to operate the switch 10. This is partly due to the fact that the distance from the rollers 28 and 32, or other conductive parts upon brackets 12 and Hi, to the tips I8 and'fll of the electrodes is substantially constant and the only material variation which occurs is due to the spacing between the electrodes.

From the foregoing description it will be seen that if the electrodes are separated and no arc exists therebetween, the potential in control circuit will build up sufficiently, depending upon thesetting of resistor 81, to energize control solenoid 19. This will effect one cycle of operation of the operating mechanism, moving the electrodes forward a very small increment of travel. The mechanism will in fact repeat its cycle of operation, if no arc exists, a sufiicient number of times to cause the electrodes to engage and the arc to 'form. If the arc is merely allowed to burn without adjustment, the carbons will grad ually wear away until the gap therebetwe'en started to exceed a predetermined distance, as governed by the setting of resistor 81, and the resistance across the gap will become so great that solenoid 19 will again act to cause a single forward step of the mechanism. This will reduce the size of the gap and lower the resistance thereof so that the voltage in control circuit 85 wiil drop to below that at which solenoid 79 becomes operative.

Normally during the use of an arc lamp or like apparatus an operator will move one or both of the electrodes manually by turning hand wheels 30 forwardly to establish the arc and then outwardly to separate the same sufficiently to produce the proper size are. The sliding contact between flange 4B and the ratchet wheel 44 allows this reverse rotation of the wheel 28 while the ratchet wheel is prevented from rotating by pawl 50. At the same time, he will also locate the are at the focal point 2| of the lens system and for such purposes, there would probably be provided in the housing (notshown) for such an instrument a dense colored glass window or the like for allowing inspection of the arc while be ing so adjusted. Fig. 2 shows one slip clutch form of manual means which may be used for allowing adjustment of the electrodes. Other equivalent means could be as readily employed.

In one form of the arc lamp employing carbons of the type and size mentioned above and with the lamp connected to a conventional volt A. C. source, it was found advantageous to arrange the arc lamp to operate on a potential in the neighborhood of 45 volts and with the resistor 8i adjusted to maintain a gap of approximately 3 to 3 mm. between the tips. The solenoid 19 and the control switch 10 are of such sensitivity that an increase in the arc gap length of as little as mm. (resulting in a voltage rise in the neighborhood of 2 to 2.5 volts across the arc) will be sufiioient to actuate control switch Hi to advance the electrodes a single step. The mechanism, accordingly, is ratioed to provide approximately A; mm. increments of advance and such small changes in arc gap length will be nearly imperceptible in the illumination resulting therefrom.

' In large projectors, flood lights and like, much heavier electrodes and amperages may be employed and the gap. spacing increased considerably, even as much as 10 to 12 mm., but the operating voltage across the arc will remain the same 40-to 65 volts) and the control circuit will. operate in the same manner when the predetermined gap length is exceeded by approximately mm., causing a building up of resistance across the arc of as little as 2 to 2.5 volts as previously mentioned.

The foregoing description has referred to an alternating current source of electrical energy primarily because the same is so universally available today, but it should be also noted that an equivalent direct current supply could as satisfactorily be employed, and such would only require minor changes in size and adjustments in order to give an arc lamp having equally satisfactory operating and control properties.

While the invention relates primarily to projectors, fiood lights and the like, it will be appreciated that the electrode or electrodes of an arc welding apparatus, are furnace or the like could be controlled by similar means, if desired, for effecting constant operation thereof. Ofcourse, in the cases where a single electrode is being actuated the arc will be maintained between this electrode and the work piece or material being welded or processed.

The extreme sensitivity and positive operation of the mechanism of the present invention combine in producing an efficient, compact, inexpensive and satisfactory means of controlling electrodes for are lamps, welding apparatus and the like. It will be manifested that the apparatus just described is capable of many uses and applications and may be modified considerably to make it suitable to the individual needs. The scope of the invention, accordingly, is to be determined not by the language or the details disclosed but by reference to the appended claims.

I claim:

1. In an apparatus of the character described having a pair of electrodes adapted to be moved toward a common point for maintaining an arc gap of substantially constant predetermined length therebetween, the combination of an actuating member for effecting movement of each electrode toward said point, driving means for actuating each member and arranged to cause a predetermined amount of forward movement of each electrode when moved from an initial position a predetermined distance in a driving direction, means for urging said driving means toward its initial position, conductors for connecting said electrodes to a source of electrical energy, a main electromagnetic means for actuating said driving means and connected to said conductors, a first normally open switch in series with said main electromagnetic means for controlling the supply of energy thereto, and a con trol circuit connected to said conductors so as to be shunted across said gap, said control circuit comprising a second normally closed switch and an electromagnetic control means in series therein, said electromagnetic control means being responsive to a potential in said control circuit of a predetermined amount and operative to effect a closing of said first switch for energizing said main electromagnetic means, said second switch being responsive to the driving movement of said main electromagnetic means for effecting an interruption of current in said control circuit.

2. In an apparatus of the character described having an electrode adapted to be moved toward an electrically conductive material for maintaining an arc gap of substantially constant predetermined length therebetween, the combination of an actuating member for effecting movement of said electrode toward said material, driving means for actuating said member and arranged to cause a predetermined amount of forward travel of said electrode during a forward stroke thereof in a driving direction from a starting position, means for urging said driving means toward its starting position, conductors for connecting said electrode and said conductive material to a source of electrical energy, a main electromagnetic means connected to said conductors and arranged to actuate said driving means, a first normally open switch in series with said main electromagnetic meansfor controlling the supply of energy thereto, and a control circuit connected to said conductors so as to be shunted across said gap, said control circuit comprising a second normally closed switch and an electromagnetic control means in series therein, said electromagnetic control means being responsive to a potential in said control circuit of a predetermined amount and operative to effect a closing of said first switch for energizing said main electromagnetic means, said second switch being responsive to the driving movement of said main electromagnetic means for effecting an interruption in current in said control circuit.

3. In an arc lamp of the character described having a pair of electrodes adapted to be moved toward a common point for maintaining an arc gap of substantially constant predetermined length therebetween, the combination of a pair of main conductors operatively connected to said electrodes, a pair of actuating members for effecting movement of said electrodes toward said point, driving means for actuating each member and arranged to cause forward movement of said electrodes when moved in a driving direction, a main electromagnetic means and a normally open switch connected in series between said conductors, said main electromagnetic means being connected to said driving means and movable through a limited driving stroke when energized for effecting a small increment of forward travel of said electrodes, means for urging said driving means in the opposite direction to effect a return stroke independently of said actuating members, a control circuit connected to said conductors and comprising a second normally closed switch, a control solenoid and an electrical resistor in series therein, said solenoid having its armature substantially horizontally disposed and normally located in a position of relatively high sensitivity relative to the electromagnetic field thereof, said Solenoid being responsive to a potential in said control circuit of a predetermined value, and connected to said first switch so as to close same when the potential in said control solenoidl reaches said value, said second switch being adjustable relative to the armature of said main electromagnetic means so as to be opened by movement thereof as same approaches the end of its driving stroke.

4. In an arc lamp of the character described having a pair of electrodes adapted to be moved toward a common point for maintaining an arc gap of substantially constant predetermined length therebetween, the combination of a pair of main conductors operatively connected to said electrodes, a pair of actuating members for effecting movement of said electrodes toward said point, driving means arranged to cause forward movement of said actuating members and electrodes when moved in a driving direction, a main electromagnetic means and a first normally open switch connected in series between said conductors, said main electromagnetic means being connected to said driving means and movable through a limited distance when energized for effecting a small increment of forward travel of said electrodes, means for urging said driving means in the opposite direction independently of said actuating members, a control circuit con-- nected to said conductors and comprising a second normally closed switch, a control solenoid and an electrical resistor in series therein, said control solenoid having its armature substantially horizontally disposed, adjustable means for regulating the normal inoperative position of said solenoid and armature so as to effect a closing of said first switch by movement of said solenoid when a potential of a predetermined value in said solenoid is reached, and additional adjustable means for limiting the amount of movement of said armature after a closing of said first switch has been effected, said second switch being disposed so as to be opened by said electromagnetic means during the driving stroke thereof.

5. In an apparatus of the character described having an electrode adapted to be moved toward an electrically conductive material for maintaining an arc gap of substantially constant predetermined length therebetween, the combination of a pair of main conductors operatively connected to said electrode and to said electrically conductive material, an actuating member for effecting movement of said electrode toward said material, driving means arranged to cause forward movement of said actuating member and electrode when moved in a driving direction, a main electromagnetic means and a first normally open switch connected in series between said conductors, said main electromagnetic means being connected to said driving means and movable through a limited distance when energized for effecting a small increment of forward travel of said electrode, means for urging said driving member in the opposite direction independently of said actuating member, a control circuit connected to said conductors and comprising a second normally closed switch and a control solenoid in series therewith, said second switch being positioned so as to be opened by driving movement of said main electromagnetic means, the armature of said control solenoid being arranged to operate said first switch, adjustabl means for regulating the normal inoperative position of said armature, and additional adjustable means for limiting the amount of movement of said armature relative to said 10 solenoid after a closing of said first switch has been effected.

6. An apparatus of the character described for use with an electrode adapted to be moved toward an electrically conductive material for maintaining an arc gap of substantially constant predetermined length therebetween, said apparatus comprising movable means for effecting forward movement of said electrode toward said conductive material when said apapratus is operatively associated therewith, driving means for actuating said movable means for causing a predetermined amount of forward travel of said electrode during a stroke thereof in a driving direction from a starting position, means for returning said driving means to said starting position after each driving stroke thereof, a main electromagnetic means and a first normally open switch connected in series in a first circuit adapted to be connected to the conductors supplying electrical energy to said electrode and to said electrically conductive material for maintaining said are gap, said main electromagnetic means being arranged to actuate said driving means when said first switch is closed, a control circuit adapted to be connected to said conductors supplying electrical energy to said electrode and said conductive material so as to be in effect shunted across said arc gap, said control circuit comprising a second normally closed switch and an electromagnetic control means in series, said electromagnetic control means being responsive to a potential in said control circuit of a predetermined amount and operative to effect a closing of said first switch for energizing said main electromagnetic means, said second switch being responsive to movement of said main electromagnetic means during said driving stroke for effecting an interruption in current in said control circuit.

ANDREW BERGMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 324,008 Clark et al Aug. 11, 1885 947,993 Kellogg Feb. 1, 1910 1,101,629 Hall June 30, 1914 1,603,244 Mole Oct. 12, 1926 1,626,472 Mole Apr. 26, 1927 1,875,066 MacFarland Aug. 30, 1932 

